The Statistics and Data Center (SDC) of the Children's Oncology Group (COG) serve two important, distinct but related functions in COG. The first is to provide statistical sciences expertise in support of COG research through a staff of experienced Ph.D. level statisticians who are faculty members at major universities. These 'faculty' statisticians collaborate with COG investigators through their membership on COG study and scientific committees. They are assisted in this function by master-level statisticians and programmers who are also employed by the SDC. The second important function of the SDC is study and data operations - i.e., the coordination of COG research studies and the timely acquisition and storage of high quality data for COG studies, and interaction with COG institutions and study committees to ensure successful completion of COG studies. A staff of information technology professionals and research coordinators accomplish this SDC function. The COG SDC consist of two logically distinct departments or divisions: The first is the statistics department, which comprises the senior (Ph.D.) statisticians and assistant (M.S.) statisticians, plus some support staff. Although functioning as a united department, the members of this department are located at four main sites: The University of Southern California (USC)/Arcadia, the University of Nebraska/Omaha, the University of Florida/Gainesville and the University of Washington. The second division is data operations. This includes the Information Systems (IS) and computing staff which supports Remote Data Entry (RDE) and other necessary computing functions. All IS and computing staff will ultimately be located in Arcadia, although for the first two years of the grant period a small number will remain in Gainesville until the consolidation in Arcadia is complete. The division also includes a staff of research coordinators, who serve as the primary managers of studies and study data in the SDC, and who serve as the primary interface between the study committees, institutions, statisticians, the study development office and Group leadership, for all matters concerning data collection and related issues for ongoing COG studies. This staff is directed by a lead research coordinator who reports to the Group Statistician.